Flex Fuel Tuning Gives A Shelby GT500 975 HP On Demand

It’s the classic dilemma for any high-horsepower build: pump gas or E85? One offers convenience, the other maximum power, but you usually have to pick a side. Late Model Racecraft showcased a 2021 Shelby GT500 that proves you can have both. LMR took a beautiful GT500 and installed their Stage 3 package with a true flex-fuel system, creating a monster that can switch from street cruiser to race-ready beast with a simple trip to the gas station.The owner’s goal was clear from the start. “He wanted something that he could drive on pump gas or E85 and just have fun on the weekends,” LMR’s Steven Fereday explained. To achieve this, the LMR team fitted the Shelby with a Kong-ported supercharger, a full fuel system, and long-tube headers. The result is an engine that screams at high RPM, a characteristic Fereday compared with another high-revving V8.

What makes this build special is its brain. Unlike typical high-power GT500s, which are often E85-only or require manually switching tune files, this car features a true flex fuel system. Steven highlighted this and said, “So, this car has a true flex-fuel sensor on it and flex fuel capability for the ECM.” The car’s computer automatically detects the ethanol content and adjusts the timing and fueling, seamlessly handling the switch between pump gas or E85.The results on the dyno were also staggering. On 93 octane, the GT500 laid down 815 rear-wheel horsepower, a number that Fereday called “no joke for most customers out there.” Then, with nothing more than a change of fuel, the power skyrocketed to over 975 rear-wheel horsepower. Steven was impressed by the difference; he noted that it was a 160 rear-wheel horsepower gain just from changing fuels.

This build settles the pump gas or E85 debate for GT500 owners by offering the best of both worlds. It offers a huge tactical advantage, as the owner can cruise on 800-plus horsepower and then, as Steven put it, “go to the gas station, put E85 in it, come back with another 160 rear-wheel horsepower like that.” This LMR Stage 3 package proves that with the right setup, you don’t have to choose; you get the everyday convenience of pump gas and the shocking power of E85 on demand.